Hydrocarbons may be injected into internal combustion engines as fuel, in order to generate power through the combustion process. Additionally, hydrocarbons may be injected into an exhaust gas assembly in order to generate heat for various devices in the exhaust gas assembly. The injected hydrocarbons may interact with components in the exhaust gas to produce heat via an exothermic reaction. Determining the optimal rate of hydrocarbon injection requires balancing multiple factors.